Manufacture of china clay



Febg27, 1923.

N. TESTRUP.

MANUFACTURE 0F`CH|NA CLAY.

2 SHEETS-SHEET l.

FILED .lUNE l R922.

@'driest clay.`

Patented eet. e7, ieee.

.Metttteetttt Application' filed June' 1,

P-lnfnian'y ceses the Washedclay having e.

Water content of sey.9O% passes to ysettling tanks .from Whichlaiter various abstractions of vclear Wet'erj and eddidjionsY ofthe lWashed clay as above, .la layerL Sonie; tour orali-'ve 'feet "deep of settled cley,v with an average Vof ny- .thing from 333"to.50%`water, is excavated -bythand'and removed infbuggies ortruclcs to the kilns or drys.

The' abo've'percentages represent. averages or' (the. complete layers'. oflvsettled clay as .11n-

-diceted7 f but Ithe Water `contentl of' @settled layer Will vary. greatly. roin'the'top tothe Ybottom `thereof and. have oundfthatthe upper pert 'of' layer niay'havee'wve'ter content whichis in the' neighbourhood'offdouble that o1 the lowery partof' thelayer.' v

v An object of .the presentinvention. isto introduce en improved process `in"Whchthe only 'is tekent. to" be..u1-ther op,- erated upon. I f` "-inother object of theinvention is to eieet .Where desired ewfurther renementiofth@ i cley'in simple and expedition'sinztnner for some purposes.

` The invention. consists in a Inethod of manufacturing china Aclay vaccording` to which clay of large Water contentl is." freed of liquid by 'separating methods such es l settlement in e VtenltiuntileiA substantial layer of increased consistency is reached; a-iter precipitated layer, say 'by ,suitable conveyor or otherdetechingmeens Without removal ofthe Wetter portion, and thedrying of seid denser clay to `any desired ldegree- `is coinpleted upon a surface;heated-say by, conipiessed evolved vapour. 'l v The invention further consists inl a method es indicated, in 'which aA drier is continuously supplied Withclay Ofadesired uniforni 'consistencyy "say by the Combined opmiete.

1 922. SerialgNO. 565,250. .ri z. n fw eatpnfin sequfncegef a plurality. eflettlinfg tanks er ether icqetnueuslv .tendujcted :pre- -Qmltatingjerlltluid sepratn@ oprations? 'llh@ tnventlon tunther .CQeSlStS 1115 Subleetf ngfeley'esebteeetltrom @dritt by mthQtlS indented .inev` it .as

is.. deposited. ein. t .St- 1et-df00ntlti0n- The nveetenelso @Qnsstsfn .impreve- -mentsn errel-.etng teeth@ imenufttettreof e'hnettyies"hernettttedeater The eeeolepenyieediagrammatic Y strev-A .iees illetttete; e.; @entretient eteletliment" et .theinveetien-- i .-ntheseidrenieet @isere .l e diretteteA matic..representante.etententes .tot treftt- .menthe/.net Clav eetl.etefftheftlried povtl f; Figure 2. Sheva-.te a. .leteetSeeleetliteil- I meti@ tteeleetel. plenaven nertlvn .elett .tion APerth/l .'11.S..CtiOI1; Qf...0nt.':ee.flff1 t drier; Figure 3 is e diagranuntic section .one .Qt-the. Sempere.-.tlttivnjte.aletetr seele-Figure 'tshewstee lefgerietile 1031@ f vertelt Carrying. Ctletltttl tregihtnient.'4

venteete effect. inthe x eiei'dfde.fret .e1-11k .at time; e@ which thedensest lclay is removed fro1n" 'the so 'that :the ofg eater 'vveter content 4 is fior-urtherfsettl nient es sliovvn ett.

The'.cleynremovefdfrom the "bottoms of y the ytg'igllksbyftlie Aconveyors.'5, 52.122 is efe or chutes c, c, c2 to the hopper d of a drum drier al and by passing between them is spread as a4 film of suitable thickness upon the drying surfaces of the two drums d2, d3 the dried powder being removed yby the scrapers e, e carried by the channels e4, e5 through which the materialvis removed from the drier by the conveyor screws e2, es. The

vapor evolved from the film of clay is drawn from the casing Z through the opening y and pipe -y by the compressor m and returned thereby at a higher pressure and temperatureto the interior of the drums d2, 0K3, by the pipe a, said pipe having branches el, a2 which enter the hollow trunnions d4, d5 'of the drums, the evolved vapor thus acting as the heating medium after starting the apparatus in the lmanner well known in connec tion with this method of heating.`

By using the densest clayv only the quantity of liquid to be expelled from the films as vapour is greatly reduced and the size of` drier necessary for the Work is thus kept small. In addition a uniform result is obtained in this drying stage and the product from the drier may be depended upon 'as being of a definite known and very small i water content, the water content in fact being reduced as far as maybe necessary for the furthe-r use to which the product is to be put. v

yThepproduct from the improved yprocess hereinbefore described would resemble generally the ordinary product at present known as commercial china clay, but for certain purposes greater refinements are required,

which heretofore have only been obtainable by treating the clay in a dierent manner during the settling stages.

Proposals have been made to effect this further refinement by creating what has.

been called colloidal clay. This has been done by the addition of certain alkalies, which have the eEectof making china clay behave las if it were colloidal, whereasthe i `of is retained by the clay, after the -clay has been standing in the ultimate settling tanks for the usual period.

This refinement of the clay is laborious and costly and unless further operations are undertaken for'thickening, filtering or otherwise separating, a larger percentage of v water has to be evaporatedin the drys.

Accordingto a further feature of the present invention the refinement of the clay is effected in the dry state after it has been removed from the drum drier, the dry clay or other gaseous material in which the vbeing introduced into an atmosphere-of air heavier mica, quartz, feldspar and other im-k i purities are allowed to separate out from the lighter china clay particles and the ultimate `product therefore-can be made of any desired degree of purity. n

For carrying out this 'further feature, the dried clay removed by the'conveyors e2, e3 is fed into and carried by anotherl conveyor g operating .in a conduit g1 and driven by gearing g2. This conveyor delivers the` clay into the yhopper 7L. of a fan y'. The dried clay may be sufficiently powdered in its transit but it may. also be subjected to -other d-isintegrating processes such as grinding or crushing if necessary, and in this powderedl condition it is delivered toy the fan with a suitable volume'of air drawnin throughthe airL inlet i@ surrounding the yfeed pipe.

rlhe delivery from the fan passes along a i conduit Z beneath which a series of vsettling chambers m, mare arranged at suitable in;

tervals, so that theheavy particles drop out v by gravitationand areselected in accordance with the particular properties of each.

cyclone n, in which the yfinestsolid matter is arrested, andthis cyclone may be fitted upon its outlet with a bag filter o lif desirable. i

In some cases settling chambers may be omitted .andy a cyclone only be employed, the speed of the air carrying the dried material being so adjusted that the heavy particles drop out at the bottom of the cyclone and only the light china clay particles and a smallproportion of minor impurities are allowed to passthrough to the hopper containing the finished article. v f

It is to be vunderstood that the steps in the methods of operation and the apparatus therefor hereinbefore described are given by At its extremity the conduit Z venters a way of example only and that alterations and additions may be effected without in any way departing from the spirit `of the invention.

Having now described my invenion what" I claim as new and desire to secure by Let` ters Patent is f l. A method of manufacturing china clay,

consisting in freeing wet clay having a large liquid content of itssuperfluous liquid -until alayer'of deposited clay of smaller average liquid content'varying through the layer is obtained, removing only the densest clay from the side of the layer remote from that on which the liquid has separated and feed-l ing said densest clayin the form'of a film 2. method of manufacturing-china clay,

consisting in freeing wet clay having a large liquid content of its superfluous liquid until a layer of deposited clay of smaller average liquid content varying through the layer is obtained, removing only the densest clay from the side of the layer remote from that on which the liquid has separated, feeding said densest clay in the form of a film on to a drying surface heated by a medium of which the temperature is only moderately in excess of the evaporating temperature of the liquid still in the clay and transporting the resulting dried powder in a current of gaseous fiuid to effect separation of various constituents in accordance with their relative weights.

- 3. A method of manufacturing china clay, consisting in freeing wetclay having a liquid content say in the neighbourhood of 90% of its superfluous liquid until a layer of deposited clay of an average liquid content of say of some 50% varying considerably from top to bottom of the layer is obtained, removing only the densest clay from the side of the layer remote from that upon which the liquid is separated, feeding said densest clay in the form of a film on to a drying surface by squeezing it between two l rotating drying cylinders and heatingfsaid cylinders by inserting therein the vapour evolved from the film after said vapour has been subjected to compression to raise its the side of the layer remote from that upon which the liquid is separatedt feeding said densest clay in the form of a film on toa drying surface by squeezing it between two rotating drying cylinders, removing said clay from the drying surface with a low liquid content permitting powdering thereof and carryingsaid powder in a gaseous vme- 1dium to effect selective separation of various constituents.

In testimony whereof I have signed my'y name to this specification.

NiLs Tns'rimr.V 

